The present invention relates to a destination navigation method used for an in-vehicle navigation system for giving a driving guidance along a route to a set designation (hereinafter referred to as a routing line to destination) and, in particular, to a destination navigation method in a case when the routing line to destination has a section requiring a lane change.
FIG. 1 is an illustration to show a destination navigation method in the prior art, for example, disclosed in Japanese Patent Laid Open Publication No. 2000-18956. As shown in FIG. 1, when a routing line to destination for connecting the present position to a destination is set in a navigation system, every time a vehicle comes near to a branch point (hereinafter referred to as a guide branch point) where a guidance is given to a driver along the routing line to destination, a driving guidance relating to the guide branch point is given, for example, by means of voice. In this case, for example, a distance to the guide branch point and a direction to turn such as xe2x80x9cxxx meter ahead, Turn to the rightxe2x80x9d are announced by voice. Further, as shown in FIG. 1, not only the distance to the guide branch point but also the position of lane to pass such as xe2x80x9cxxx meter ahead, To xxxx, Go to right end lanexe2x80x9d is announced by voice.
Since the destination navigation method used in the navigation system in the prior art gives the driver the driving guidance in the manner described above, even in the case when the routing line to destination has a section requiring a lane change, it gives the driver only a guidance of the lane to pass at an every predetermined appropriate timing when the vehicle comes near to the guide branch point. However, in a case when there is a road having many lanes on the routing line to destination and the vehicle is driven along the routing line to destination, if a distance for an entryway or a junction (exit way) is short to/from a highway having many lanes along the routing line to destination, it is necessary to make a large lane change in a short distance but, even in this case, as described above, the destination navigation method in the prior art does not give a special alarm but only gives an appropriate guidance of a lane change. Therefore, the destination navigation method in the prior art requires the driver to make a large lane change in a short time without informing the driver of the necessary large lane change, in advance, which presents a problem of raising the possibility that the driver, in particular, an unskilled driver who gets a driving license a short time ago, is given a mental fatigue and is uselessly tired in driving.
Further, when the driver searches a route from the present position of the vehicle to the destination, the destination navigation method in the prior art uses a travel distance, a driving time, expenses including a highway toll (hereinafter referred to as a cruising toll) as evaluation indexes for selecting the routing line to destination, but does not take into account whether or not the routing line to destination includes a section requiring the driver to make a large lane change in a short distance (hereinafter referred to as a short-distance lane change section) in performing a search for the routing line to destination. Therefore, the destination navigation method in the prior art presents a problem that it can not respond to the request of the driver who desires to avoid such a short-distance lane change section.
The present invention has been made to solve the problem described above, and it is an object of the present invention to provide a destination navigation method for informing or warning a driver that the vehicle is coming near to the short-distance lane change section at the time when a vehicle comes near to a short-distance lane change section.
Further, it is another object of the present invention to provide a destination navigation method for judging whether or not a set routing line to destination includes a short-distance lane change section and for changing the set routing line to destination to a bypath including no short-distance lane change section according to the selection of a driver.
A destination navigation method in accordance with the present invention includes a step of judging whether or not one searched route or a plurality of searched routes include a short-distance lane change section.
This makes it possible to set a routing line to destination on the basis of the presence or absence of the short-distance lane change section, and thus can produce an effect of responding to the request of a driver to desire to bypass the short-distance lane change section.
The destination navigation method in accordance with the present invention further includes a step of making the driver select whether or not the driver avoids passing the short-distance lane change section.
This make it possible to reflect a driver""s intention of avoiding or accepting passing the short-distance lane change section to the setting of the routing line to destination, and thus can produce an effect of setting the routing line to destination in accordance with the driver""s intention.
The destination navigation method in accordance with the present invention further includes a step of judging whether or not one route or a plurality of routes among the routes for connecting the present position to the destination include the short-distance lane change section and a step of making the driver select whether or not the driver avoids passing the short-distance lane change section only in the case when the route is judged as including the short-distance lane change section.
This makes it possible urging the driver to select the route only in the case when the route having a possibility of being set as the routing line to destination includes the short-distance lane change section and thus can produce an effect of eliminating the need for asking an unnecessary selection of the driver and of improving the convenience of a navigation system.
The destination navigation method in accordance with the present invention further includes a step of judging whether or not one route or the plurality of routes for connecting the present position to the destination have an appropriate route including no short-distance lane change section.
Thereby, in the case when the driver desires to avoid passing the short-distance lane change section, if an appropriate route including no short-distance lane change section is found, it is possible to automatically set the route as the routing line to destination, and thus to produce an effect of setting the routing line to destination that the driver desires without asking an unnecessary selection of the driver.
The destination navigation method in accordance with the present invention further includes a step of informing the driver that there is the short-distance lane change section on the routing line to destination in a case when the set routing line to destination includes the short-distance lane change section, by an use of image information or voice information.
Thereby, it make possible for the driver to recognize in advance that the driver passes a route including the short-distance lane change section and thus to produce an effect of making the driver prepare driving for passing the short-distance lane change section and of reducing the mental fatigue of the driver.
The destination navigation method in accordance with the present invention further includes a step by which the driver is given an alarm or a driving guidance relating to the short-distance lane change section every time the driver comes near to the short-distance lane change section in the case when the set routing line to destination includes the short-distance lane change section.
Thereby, it makes possible to call a driver""s attention before the driver passes the short-distance lane change section and thus to produce an effect of improving safety in driving a vehicle.
The destination navigation method in accordance with the present invention further includes a step of displaying one route or a plurality of routes including a short-distance lane change section and one route or a plurality of routes including no short-distance lane change section in such a manner that they can be discriminated from each other, and a step of making the driver select one route out of the plurality of routes displayed in the said displaying step.
Thereby, even in the case when the route including no short-distance lane change section is judged as being not appropriate, the route can be set as the routing line to destination by the selection of the driver, and it is possible to produce an effect of expanding the alternatives of cruising routes and improving the effectiveness of the navigation system.